1. Field of the Invention
The present invention relates to an electronic system, and more particularly, to a signal outputting circuit of the electronic system.
2. Description of the Prior Art
The electro-static discharge (ESD) refers to the charge transfer phenomenon caused by objects with different electro-static potentials approaching each other or contacting each other directly. In recent years, with the rapid development of the technology, the microelectronic technique has been extensively applied and the electromagnetic environment has become more and more complex. As a result, the problems caused by the ESD in electronic products have attracted more and more attentions.
The interferences of the ESD on circuits are divided into two situations. In one situation, the ESD current passes the circuits directly to cause damages. In the other situation, the electromagnetic field induced by the ESD current disturbs the circuits by ways of a capacitance coupling, an inductance coupling, and a space radiation coupling, etc.
Generally, static electricity with different levels exists in humans and environments. When the accumulated static electricity reaches to a certain amount and then is contact with electronic devices, a discharge phenomenon will happen instantaneously. This natural discharge phenomenon will cause electronic devices, such as computers, mobile phones, PDAs or liquid crystal screens, etc, damaged seriously or work improperly.
For example, if the liquid crystal display system is interfered by the ESD, then the interference may further affect the chip circuit in the video system, and the signals, transmitted from the image processing circuit to the liquid crystal screen, are disturbed to generate errors. The abnormal signals may cause twinkling or unstable display, and may further affect the displaying property of the screen.